Methods of determining the coefficient of water conductivity in soils

The paper is aimed to consider the theory and methods of determining the coefficients of water conductivity and filtration. Soil columns and lysimeters were used for this purpose. It is shown that even a slightly expressed decrease in the moisture content can lead to decreasing the water conductivity in soil. In the range of high values of the moisture potential the coefficient of water conductivity is significantly higher for light-textured soils, on the contrary, within the range of middle and low values it seems higher for loamy soils. The maximum of water conductivity in any soil is close to filtration coefficients, but its minimum tends to zero. The coefficients of water conductivity and filtration become usually close under conditions of descending flow when the moisture is equal to the maximum water capacity or close to it

Peculiarities in water use and supply of differentecological plant groups

Every ecological group of plants including hygrophytes, mesophytes and xerophytes is characterized by a definite narrow interval of the soil water potential, in which the values of relative transpiration cannot be lower than the optimal level (1.0-0.9). These intervals take into account the influence of soil properties (moisture potential) and meteorological conditions (transpiration) and can be used as optimal indices for the water supply of plants. The peculiar soil water uptake by plants has been studied to show that the soil water and its intensive uptake become increasing but its “dead” reserve decreasing from hygrophytes towards mesophytes and then xerophytes. It is worth emphasizing that the decline in the growth and accumulation of useful products by plants occur due to decreasing the content of soil water to the lower boundary of optimal moistening. The further decrease in soil moisture leads to permanent and then ultimate wilting of plants. Under study were also intervals for soil water potential corresponding to the moisture of ultimate wilting of different ecological plant groups. Lettuce (hygrophyte) is becoming dead when the content of soil water is equal to 1.5, oat (mezophyte) - 1.0 and xerophytes - lower than 1.0 of the wilting moisture. The method of “vegetative miniatures” widely adopted now is imperfect and can be performed only for preliminary notions about the lower limit for plant availability of the soil water

THE PECULIAR FORMATION OF THE WATER REGIME IN SODDY-PODZOLIC SOIL IN DIFFERENT POSITIONS OF SOIL CATENA

Under consideration is the dynamics of moisture reserves and soil water potential in different parts of the catena represented by soddy-podzolic slightly gleyed soil. Peculiar features in the development of moisture reserves have been identified in different elevated positions of this catena and their transformation in time depending on the weather conditions. It is shown that the dynamics of soil water potential in dependence on the depth of the soil profile and time well agrees with the peculiar changes in moisture reserves

REGULARITIES IN ACCUMULATION, LOSS AND RETURN OF WATER AND CHEMICAL SUBSTANCES DURING THE WATER EXCHANGE IN SOIL

The experimental studies permitted to determine the ratio between infiltration and transpiration of the ground water in a soddy podzolic soil, that accounts for 0.3-0.6 under dried conditions of atmospheric moistening, 2.6-2.9 as an average value for many years and 2.6-2.9 under moderately wet conditions. The loss of potassium, calcium, magnesium, zinc and manganese under the grass stand was calculated as 0.95, 89.0, 37.7, 1.42 and 1.40 kg/ha/yr respectively. Due to capillarity the root layer of this soil receives 0.19 kg/ha of potassium or 20% from its loss with water infiltration, 16.4% of magnesium, 15.0% of calcium, 13.4% of zinc and 9.0% of manganese. It is shown that the water transpiration in case of the close underground water level leads to rupture of capillary links. With increasing the soil thickness in lysimeter the water infiltration and the nitrate leaching become declined both under grass and beangrass stands

Anthropic factor influence on evolution of drained dernovo-podzolic soils of Upper Volga Lowland

Hydromorphic dernovo-podzolic soils, placed in Upper Volga Lowland (Tver region) are investigated. It is established reasons of land melioration effect decrease in Noblackland zone of Russian Federation. It is studied mineralization of drained flow in year season. It is determined factor complex on improvement drained soil production. It is recommended to build no only draining system, but also system with two-way soil water regime. If application of mineral fertilizers in soil norm N200P150K150 agrochemical indexes improve and yield oats increase in 3 once

The influence of water-holding layer on the water supply of potatoes in loam-sandy soils of Oman

The paper is devoted to the analysis and evaluation of peculiar features of the water regime in loam-sandy soils of Oman. The total water volume taken up by potatoes has been determined in different modes of pre-irrigation soil moisture (70, 80% of MWC and 70-80-70% of MWC) and in dependence on the water-holding layer consisting of natural materials. It is shown that the most favorable conditions for water supply of potatoes, taking into account the economical use of irrigation water, can be created by differentiation of pre-irrigation soil moisture in inter-phase periods at a level of 70-80-70% of minimum water capacity (MWC). At the same time, sapropel should be used as a water-holding layer, which increases the potatoes yield at least by 10%

Water Potential in Conditions of Soil Solution Phase Change and During the Year

The dynamics of the soil water potential and soil temperature at different depths during the year was studied. As the object of the investigation we took soddy-podzolic clay loamy weakly gleyed soils of Zelenogradskiy base of Soil Science Institute. The data of soil water and temperature were derived from the automated meteorologic station “VantagePro2”. In conditions of the sustainable state of the other components of the environment, we discovered sharp spasmodic increase of the soil water potential at the passing of temperature values to the range below zero, i.e., in conditions of the phase overpass of the soil solution. All of the types of soil water potential changes (slow and rapid, significant and insignificant) occur due to the changes (decrease or increase) of the water content and soil temperature. For the first time in our country the thermohydrophysical phenomenon of (thermodynamic process) of sharp (at 5-6 times) and rapid (practically immediate) increase of the water potential after the overpass of the temperature over zero from the area of positive values to the negative values is discovered and described. The knowledge of specificities of the dynamics of soil water potential due to the temperature will allow us to plan the terms and norms of watering

SOME ASPECTS OF DIFFERENTIAL DIAGNOSTICS OF GIANT-CELL TUMOUR, OSTEOCYSTOMA AND OSTEOSARCOMA

The problems of timeliness and correctness of diagnostics of bone tumours, as well as therapeutic decision deserve the most careful consideration. The present research concerns the detection of criteria of differential diagnostics of giant-cell tumours, osteocystoma and osteosarcoma (according to the literary data). According to the literature the study of clinical and radiologic diagnostics, allowed to work out differential and diagnostic tables of signs and algorithms of diagnostics of giant-cell tumours, osteocystoma and osteosarcoma. It enabled to detect a therapeutic and diagnostic approach to patients with bone tumours

Synthesis of CuAl-LDHs by Co-Precipitation and Mechanochemical Methods and Selective Hydrogenation Catalysts Based on Them

The paper presents the results of the synthesis and study of CuAl layered double hydroxides (LDHs) as well as their application as catalysts for the selective hydrogenation of crotonaldehyde. Phase-homogeneous LDHs were obtained by co-precipitation and mechanochemical methods, and critical parameters ensuring the formation of the target product were identified. In the case of coprecipitation, the formation of LDH is most affected by the pH of the reaction medium and the CO32−/Al3+ ratio. The optimal CO32−/Al3+ ratio is ca. 0.5–0.8 and pH 9.5–10.0. When mechanochemical synthesis is used, at 500 m·s−2 and 60 min, it is possible to obtain a single-phase CuAl LDH, whereas at higher energies, LDH is destroyed. The mechanochemical method makes it possible not only to reduce the synthesis time and the amount of alkaline wash water but also to obtain more dispersed copper particles with a higher hydrogenating activity. The conversion of 2-butenal (T = 80 °C, P = 0.5 MPa, 180 min, ethanol) for this sample was 99.9%, in contrast to 50.5% for the catalyst obtained by co-precipitation. It is important that, regardless of the conversion, both catalysts showed high selectivity (S = 90–95%) for the double bond hydrogenation